StarChild Question of the Month for March 2003

Question:

When did the first stars form in the universe?

Answer:

Results from NASA's Wilkinson Microwave Anisotropy Probe (WMAP) released
in February 2003 show that the first stars formed when the universe was
only about 200 million years old. Observations by WMAP also revealed that the
universe is currently about 13. 7 billion years old. So it was very early
in the time after the Big Bang explosion that stars formed.

Observations reveal that tiny clumps of matter formed in the baby
universe; to WMAP, these clumps are seen as tiny temperatures differences of
less than one-millionth of a degree. Gravity then pulled in more matter
from areas of lower density and the clumps grew. After about 200 million
years of this clumping, there was enough matter in one place that the
temperature got high enough for nuclear fusion to begin - providing the
engine for stars to glow.

This result surprised many scientists who thought that it would have
taken much longer for gravity to pull enough matter together to make a
star.

This animation (5.0 MB) shows how the structure of the universe evolved
from WMAP's "baby picture" of the universe. Matter clumps under the
force of gravity, then the first stars
ignite, and finally the structures of galaxies
form. (Credit: NASA/WMAP Science Team)